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Fault weakening caused by smectite swelling
| Title: | Fault weakening caused by smectite swelling |
| Authors: | Kameda, Jun Browse this author | | Uno, Masaoki Browse this author | | Conin, Marianne Browse this author | | Ujiie, Kohtaro Browse this author | | Hamada, Yohei Browse this author | | Kimura, Gaku Browse this author |
| Keywords: | 2011 Tohoku-Oki earthquake | | Fault strength | | Smectite | | Swelling |
| Issue Date: | 2-Dec-2019 |
| Publisher: | Springer |
| Journal Title: | Earth planets and space |
| Volume: | 71 |
| Issue: | 1 |
| Start Page: | 131 |
| Publisher DOI: | 10.1186/s40623-019-1108-5 |
| Abstract: | The large slip along the shallow subduction interface during the 2011 Tohoku-Oki earthquake (M(w)9.0) caused a huge tsunami that struck the northeast coast of Honshu, Japan. The Integrated Ocean Drilling Program Expedition 343 JFAST program revealed that the fault zone is composed primarily of smectite. Our swelling experiments using the fault material demonstrated that the swelling pressure systematically increases with a decrease in sample porosity. Based on in situ porosity estimations in the IODP borehole, the swelling pressure of the fault is as high as 8 MPa, which is comparable to the effective normal stress at the drill site (similar to 7 MPa). This also suggests that the modified effective confining pressure of the fault is quite low or potentially zero, meaning that fault strength is governed mainly by cohesion rather than frictional strength. The fault may therefore be intrinsically weak, which could enhance the coseismic displacement toward the trench when earthquake slip propagates from depth. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/79608 |
| Appears in Collections: | 理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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